CN108623644B

CN108623644B - Paulomycin derivatives and preparation method and application thereof

Info

Publication number: CN108623644B
Application number: CN201810677960.XA
Authority: CN
Inventors: 陈义华; 唐越; 王敏
Original assignee: Institute of Microbiology of CAS
Current assignee: Institute of Microbiology of CAS
Priority date: 2018-06-27
Filing date: 2018-06-27
Publication date: 2020-11-03
Anticipated expiration: 2038-06-27
Also published as: CN108623644A

Abstract

The invention discloses paloci derivatives, a preparation method and application thereof. The structural formula is shown as formula I. The invention adopts the method of directly adding N-acetyl cysteamine into Streptomyces paulus NRRL8115 high-yield strains which are producing bacteria of paulomycin to obtain four new-structure paulomycin derivatives. Antibacterial activity experiments show that MICs of palsimycin A and B to test strains and MICs of paulomycin A and B are at the same level. Acid-base stability experiments show that both palsimycin A and B, C, D are more stable than paulomycin A and paulomycin B under the same conditions. The method avoids the unstable puromycin from being directly separated and purified from the fermentation liquor, and the added SNAC is easy to obtain and has no toxicity to cells, and does not influence the growth of thalli.

Description

Paulomycin derivatives and preparation method and application thereof

Technical Field

The invention relates to paulomycin derivatives, a preparation method and application thereof.

Background

Paulomycin is a glycoside natural product with a special structure produced by streptomyces, and mainly comprises an A ring (ring A), acetylated allose (acetylated D-allose), paulonic acid (paulonic acid) and paulomycin (as shown in figure 1). Paulomycin has good antibacterial activity against gram-positive bacteria, such as Staphylococcus aureus, Streptococcus pyogenes, Staphylococcus epidermidis, etc., and bacteria resistant to penicillin, streptomycin, neomycin, macrolide, etc., and can be used alone or in combination with other antibacterial agents for preventing or alleviating such bacterial infections as urinary system infection, chlamydia infection. In addition, animal experiment results show that the paulomycin has good inhibition effect on tumor cells such as P-388 leukemia.

The paulomycin is easily degraded in an alkaline solution to lose the biological activity due to the fact that the paulonic acid part contains an isothiocyanic group (N ═ C ═ S), such as paulomycin A and paulomycin B. Subjecting isothiocyanato group to H₂The biological activity of the paulomycin analogue U-77802 obtained by S modification is two orders of magnitude weaker than that of paulomycin A and paulomycin B. Paulomycin analogs Paulomycin A and Paulomycin B obtained by modifying Paulomycin acid parts with N-acetyl L-cysteine are superior to Paulomycin A and Paulomycin B in stability level, but the antibacterial activities of the Paulomycin A and Paulomycin B are lower by one order of magnitude than those of Paulomycin A and Paulomycin B. In 2017, 273a was isolated from a mutant strain deficient in both anthranilate synthase and isochorismate_2α、273a_2βThe intramolecular cyclization product of (1-4), which contains five-membered heterocyclic ring, the structure of the compound 1-4 is more stable than that of paulomycin A, B, but the activity against gram-positive bacteria is reduced. Therefore, the structural modification of the paulomycin can obtain the paulomycin analogue with stable structure and high antibacterial activity, and the application of the natural product in the clinical medicine aspect can be greatly promoted.

Disclosure of Invention

One object of the present invention is to provide palsimycins, a palsimycins, which is a paulsomycin derivative.

The structural formula of palsimycins serving as paulsomycin derivatives provided by the invention is shown as a formula I:

wherein R is₁Selected from any one of the following groups:

R₂selected from any one of the following groups:

R₃selected from any one of the following groups:

when R is₁Is a1, R₃Is a3 or b 3.

When R is₁Is any one of b1-f1, R₃Is a 3.

Preferably, the paosimycin derivative, palsmimycins, is palsmimycin A, palsmimycin B, palsmimycin C or palsmimycin D, and the structural formula is shown as follows:

pharmaceutically acceptable salts, esters and prodrugs of palsimycins, which are paulsomycin derivatives shown in the formula I, also belong to the protection scope of the invention.

The term "pharmaceutically acceptable salt" as used herein refers to salts which are, within the scope of sound medical judgment, suitable for contact with the tissues of humans and lower animals without excessive toxicity, irritation, allergic response, and the like, commensurate with a reasonable benefit/risk ratio.

The term "pharmaceutically acceptable ester" as used herein refers to esters that hydrolyze in vivo and include those that break down readily in the human body to yield the parent compound or a salt thereof.

The term "pharmaceutically acceptable prodrugs" as used herein refers to those prodrugs of the compounds of the present invention which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of humans and lower animals without excessive toxicity, irritation, allergic response, and the like, commensurate with a reasonable benefit/risk ratio, and effective for their intended use, and the potentially zwitterionic forms of the compounds of the present invention. The term "prodrug" refers to a compound that is rapidly converted in vivo, e.g., by hydrolysis in blood, to yield the parent compound of the above formula.

The invention also aims to provide a preparation method of palsimycins which is the palsimycins derivative shown in the formula I.

The preparation method of palsimycins serving as paulsomycin derivative shown in the formula I comprises the following steps: 1) streptomyces paulsus NRRL8115 (i.e., "Streptomyces paulsus NRRL8115CIM 3007" in the literature) is described in the following documents: performing fermentation culture of the Identification and Analysis of the Paulomyces biosynthetic Gene Cluster and Titer Improvement of the Paulomyces in Streptomyces NRRL 8115) strain in a liquid culture medium containing N-acetylcysteamine (SNAC), and collecting a fermentation liquid;

2) centrifuging the fermentation liquor, collecting supernatant, extracting the supernatant with ethyl acetate, collecting ethyl acetate phase, drying and concentrating to obtain a crude extract; separating and purifying the crude extract by silica gel column chromatography, wherein the eluent of the silica gel column chromatography sequentially comprises the following components: petroleum ether with the volume of 1 time of the column, mixed liquid of petroleum ether and ethyl acetate with the volume ratio of 1:1 with the volume of 1-1.5 times of the column, mixed liquid of ethyl acetate and methanol with the volume ratio of 1:1 with the volume of 1-1.5 times of the column, and methanol with the volume ratio of 1:1 with the volume of 1 time of the column, collecting elution components eluted by the mixed liquid of ethyl acetate and methanol with the volume ratio of 1:1, and concentrating to obtain concentrate;

separating the concentrate by C18 reversed phase packed column chromatography, wherein the elution phases are sequentially: water, acetonitrile-water solution with volume fraction of 10% in 1 time of column volume, acetonitrile-water solution with volume fraction of 30% in 1.5-2 times of column volume, acetonitrile-water solution with volume fraction of 50% in 1-1.5 times of column volume, acetonitrile in 1-1.5 times of column volume and methanol in 2-2.5 times of column volume, collecting elution components eluted by the acetonitrile-water solution with volume fraction of 50%, removing an organic phase, and drying to obtain a crude separation product;

3) preparing the crude separation product into a solution by taking acetonitrile as a solvent; then separating by using a reversed-phase high performance liquid chromatography, taking acetonitrile and water containing 0.06% of acetic acid as mobile phases, eluting the acetonitrile and the water containing 0.06% of acetic acid according to a volume ratio of 4:6 at equal concentration, sequentially collecting elution components with retention time of 12.5-13.0 min as a component 1, collecting elution components with retention time of 13.4-14.0 min as a component 2, collecting elution components with retention time of 17.2-17.9 min as a component 3, collecting elution components with retention time of 18.2-19.3 min as a component 4, collecting elution components with retention time of 21.0-21.8 min as a component 5, collecting elution components with retention time of 19.4-19.8 min as a component 6, collecting elution components with retention time of 20.2-20.8 min as a component 7, and collecting elution components with retention time of 24.0-26.0 min as a component 8;

4) combining the component 3 and the component 4, performing secondary refining by using a reversed-phase high performance liquid chromatography, performing equal concentration gradient elution by using acetonitrile and water containing acetic acid with the mass fraction of 0.06% as mobile phases and using the acetonitrile and the water containing the acetic acid with the mass fraction of 0.06% according to a volume ratio of 43:57, and collecting an eluent with the retention time of 12.0-13.0 min; concentrating and drying to obtain the palsmimycin A;

combining the component 1 and the component 2, performing secondary refining by using a reversed phase high performance liquid chromatography, taking acetonitrile and water containing acetic acid with the mass fraction of 0.06% as mobile phases, and performing gradient elution by using the acetonitrile and the water containing acetic acid with the mass fraction of 0.06% according to the acetonitrile percentage in the following time program: 35% in 0-3 min; 35-40% of 3-8 min; 8-13 min, 40% -43%; 13-20 min, 43% -50%; 20-22 min, 50% -100%; 22-24 min, 100%; 24-26 min, 100% -50%; 26-30 min, 50-35%. Collecting the eluent with the retention time of 18.0-19.0 min; concentrating and drying to obtain the palsmimycin B;

combining the component 6 and the component 7, performing secondary refining by using a reversed-phase high performance liquid chromatography, performing equal-concentration gradient elution by using acetonitrile and water containing acetic acid with the mass fraction of 0.06% as mobile phases according to a volume ratio of 46:54, and collecting an eluent with the retention time of 11.5-13.0 min; concentrating and drying to obtain the palsmimycin C;

performing secondary refining on the component 5 by using a reversed-phase high performance liquid chromatography, performing equal concentration gradient elution by using acetonitrile and water containing acetic acid with the mass fraction of 0.06% as mobile phases according to a volume ratio of 57:43, and collecting an eluent with the retention time of 7.3-7.9 min; concentrating and drying to obtain the palsmimycin D.

In the step 1) of the method, the volume fraction of the N-acetylcysteamine in the liquid culture medium containing the N-acetylcysteamine (SNAC) is 0.1-0.2%.

The conditions of the fermentation culture are as follows: culturing at 28 ℃ for 36-48 h.

In step 1) of the above method, the liquid medium is an R5 α fermentation medium. The composition of the R5 alpha fermentation medium per liter is: 100g of sucrose, 10g of glucose, 10.2g of magnesium chloride hexahydrate, 21g of 3-N-morpholinopropanesulfonic acid, 5g of yeast extract, 0.25g of potassium sulfate, 0.1g of acid hydrolyzed casein, 2mL of trace element liquid and sodium hydroxide for adjusting the pH value to 6.85; wherein, the ratio of trace element liquid/liter: 40mg of zinc chloride, 200mg of ferric chloride hexahydrate, 10mg of copper chloride dihydrate, 10mg of manganese chloride tetrahydrate, 10mg of sodium tetraborate decahydrate and 10mg of ammonium molybdate tetrahydrate.

The inoculation amount of the Streptomyces paulus NRRL8115 is 2-4%.

The Streptomyces paulus NRRL8115 strain also comprises a step of preparing a Streptomyces paulus NRRL8115 seed solution before inoculation, and the method comprises the following specific steps: inoculating Streptomyces paulus NRRL8115 strain spores into a GS-7 seed liquid culture medium, and culturing at 28 ℃ for 48 h;

wherein, GS-7 seed culture medium component/L: pharmamedia medium 20g, glucose 20g, ammonia to adjust pH to 7.2.

In the step 3), the chromatographic conditions of the reversed-phase high performance liquid chromatography are as follows: the chromatographic column is Aglient Zorbax SB-C18 with specification of 9.4 × 250mm and 5 μm; the flow rate was 2 mL/min.

Still another object of the present invention is to protect palsimycins, a palsimycins derivative represented by formula I, for medical use.

The medicine application of paosimycins which is a palsimycins derivative shown in the formula I comprises the following aspects: 1) the application in the preparation of antibacterial drugs; 2) application in preparing antitumor (such as leukemia) medicine is provided.

The antibacterial drug is an antibacterial drug.

The bacteria are gram-positive bacteria, specifically Staphylococcus aureus (Staphylococcus aureus), Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis (Staphylococcus epidermidis), Streptococcus faecalis (Enterococcus faecium), Streptococcus pyogenes (Streptococcus pyogenenes), Streptococcus pneumoniae (Streptococcus pneumaniae), non-cocci, and the like, and the gram-positive bacteria are not limited to the specific species described above.

The antibacterial agent is used for preventing and/or treating inflammation such as urethritis and infection such as chlamydia infection caused by coccus such as Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and non-coccus.

The invention also protects a class of antibacterial drugs.

The active ingredient of the antibacterial drug comprises palsimycins which is paulsomycin derivative shown in formula I of the invention.

The active ingredients of the antibacterial drug can also comprise other antibacterial drugs.

Paulomycin derivatives represented by formula I can be used alone or in combination with other antibacterial agents for preventing or treating inflammation and infection caused by gram-positive bacteria resistant to penicillin, streptomycin, neomycin, macrolide, etc.

The medicament may further include pharmaceutically acceptable diluents, excipients, fillers, binders, wetting agents, disintegrants, absorption enhancers, surfactants, adsorption carriers, lubricants, synergists, additives, solvents, and the like. In the preparation of the antibacterial agent, an effective dose of the compound may be mixed with pharmaceutically acceptable diluents, excipients, fillers, binders, wetting agents, disintegrants, absorption enhancers, surfactants, adsorption carriers, lubricants, synergists, additives, solvents, etc. to prepare various pharmaceutical preparations. The medicine can be in the form of oral preparation such as tablet, capsule, soft capsule, powder, granule, fine granule, liquid, pill, emulsion or suspension, or non-oral preparation such as injection (such as powder, water solution or oil) suppository, ointment, plaster, patch, spray, tincture or eye drop. These preparations can be obtained by conventional methods well known to those skilled in the art. The administration route can be oral, transdermal, intravenous or intramuscular injection.

Paulomycin consists of an A ring (ring A), acetylated D-allose motif, Paulonic acid and Paulomycin, wherein the carbon-carbon double bond and the isothiocyanic group N ═ C ═ S part of Paulonic acid part can perform addition reaction with nucleophilic groups such as-SH and-NH to generate the Paulomycin derivative. As shown in fig. 2, when paulomycin B undergoes an addition reaction with a molecule of SNAC, SNAC may be added to the carbon-carbon double bond of the paulomycin site or to the isothiocyanato N ═ C ═ S site; when paulomycin B reacts with two molecules of SNAC, SNAC may add simultaneously to the carbon-carbon double bond position of the paulonic acid site and the N ═ C ═ S group. Furthermore, when SNAC is added to the carbon-carbon double bond of the paul acid site, making C2", C3" chiral centers, results in a paul mycin B analog of different chirality.

According to the invention, small molecular thiol compound N-acetylcysteamine (SNAC) is added into fermentation liquor of a streptomyces paulomycin producing strain NRRL8115 high-yield strain, and the new structural compounds palsimycin A, palsimycin B, palsimycin C and palsimycin D (as shown in figure 3) are obtained through fermentation, separation, purification and structural analysis. Antibacterial activity experiments show that the Minimum Inhibitory Concentration (MIC) of the palsimycin A and the palsimycin B on staphylococcus aureus and other test strains is at the same level as the MIC values of the paulomycin A and the paulomycin B. Acid-base stability experiments show that both palsimycin A and B, C, D are more stable than paulomycin A and paulomycin B under the same conditions. Therefore, the invention obtains more stable paulomycin derivatives without changing the bioactivity.

The invention aims to modify the structure of paulomycin, and improve the stability of paulomycin while maintaining the biological activity of paulomycin. The invention has the advantages that: the stability of the paulomycin is improved while the biological activity of the paulomycin is not changed.

The invention adopts the method that small molecular thiol compound N-acetylcysteamine (SNAC) is directly added into the streptomyces NRRL8115 high-yield strain which is the bacteria producing paulomycin, and four new-structure paulomycin derivatives are obtained. Antibacterial activity experiments show that the Minimum Inhibitory Concentration (MIC) of the palsimycin A and the palsimycin B on the test strains is at the same level as the MIC values of the paulomycin A and the paulomycin B. Acid-base stability experiments show that both palsimycin A and B, C, D are more stable than paulomycin A and paulomycin B under the same conditions. The method avoids the direct separation and purification of unstable paulomycin from the fermentation liquor, and the added small molecular compound SNAC is easy to obtain and has no toxicity to cells, and does not influence the growth of thalli.

Drawings

FIG. 1 is a structural formula of Paulomycins and analogs thereof.

FIG. 2 shows the reaction of Paulomycin B with SNAC.

FIG. 3 shows COSY, HMBC and UV spectra (112. mu.M, acetonitrile) of palsmimycin A prepared in example 1.

FIG. 4 is a high resolution mass spectrum of palsmimycin A prepared in example 1.

FIG. 5 is a drawing of palsmimycin A prepared in example 1¹H NMR spectrum.

FIG. 6 is a drawing of palsmimycin A prepared in example 1¹³C NMR spectrum.

FIG. 7 is a COSY spectrum of palsmimycin A prepared in example 1.

FIG. 8 is an HSQC spectrum of palsmimycin A prepared in example 1.

FIG. 9 is an HMBC profile of palsmimycin A prepared in example 1.

FIG. 10 shows COSY, HMBC, and UV spectra (86. mu.M, acetonitrile) of palsmimycin B prepared in example 2.

FIG. 11 is a high resolution mass spectrum of palsmimycin B prepared in example 2.

FIG. 12 is a drawing of palsmimycin B prepared in example 2¹H NMR spectrum.

FIG. 13 shows example 2Preparation of palsmimycin B¹³C NMR spectrum.

FIG. 14 is a COSY spectrum of palsmimycin B prepared in example 2.

FIG. 15 is an HSQC spectrum of palsmimycin B prepared in example 2.

FIG. 16 is an HMBC profile of palsmimycin B prepared in example 2.

FIG. 17 shows COSY, HMBC and UV spectra (53. mu.M, acetonitrile) of palsmimycin C prepared in example 3.

FIG. 18 is a high resolution mass spectrum of palsmimycin C prepared in example 3.

FIG. 19 is a photograph of palsmimycin C prepared in example 3¹H NMR spectrum.

FIG. 20 shows COSY, HMBC and UV spectra (56. mu.M, acetonitrile) of palsmimycin D prepared in example 4.

FIG. 21 is a high resolution mass spectrum of palsmimycin D prepared in example 4.

FIG. 22 is a photograph of palsmimycin D prepared in example 4¹H NMR spectrum.

FIG. 23 is a drawing of palsmimycin D prepared in example 4¹³C NMR spectrum.

FIG. 24 is a COSY spectrum of palsmimycin D prepared in example 4.

FIG. 25 is an HSQC spectrum of palsmimycin D prepared in example 4.

FIG. 26 is an HMBC profile of palsmimycin D prepared in example 4.

Detailed Description

The method of the present invention is illustrated by the following specific examples, but the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included within the scope of the present invention.

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Streptomyces paulus NRRL8115 (i.e., "Streptomyces paulus NRRL8115CIM 3007" in the literature) used in the following examples is described in the following documents: identification and catalysis of the Paulomycin biosynthesis Gene Cluster and Titer Improvement of the Paulomycin in Streptomyces NRRL 8115.

Example 1 isolation and purification of palsmimycin A and evaluation of biological Activity and stability

1) Fermentation of

Inoculating paulus NRRL8115 high-yield strain spores into a GS-7 seed liquid culture medium, carrying out shake culture at 28 ℃ for 48h, inoculating 4% of the spores into a 500mL conical flask filled with 100mL of R5 alpha fermentation culture medium, adding 0.1-0.2% (V/V) of SNAC, carrying out shake culture at 28 ℃ for 4d, and carrying out total fermentation for 50L.

Wherein, GS-7 seed culture medium component/L: pharmamedia medium 20g, glucose 20g, ammonia to adjust pH to 7.2. R5 α medium composition/L: 100g of sucrose, 10g of glucose, 10.2g of magnesium chloride hexahydrate, 21g of 3-N-morpholinopropanesulfonic acid, 5g of yeast extract, 0.25g of potassium sulfate, 0.1g of acid hydrolyzed casein, 2mL of trace element liquid and sodium hydroxide for adjusting the pH value to 6.85; wherein, the ratio of trace element liquid/liter: 40mg of zinc chloride, 200mg of ferric chloride hexahydrate, 10mg of copper chloride dihydrate, 10mg of manganese chloride tetrahydrate, 10mg of sodium tetraborate decahydrate and 10mg of ammonium molybdate tetrahydrate.

The preparation method of the N-acetylcysteamine (SNAC) comprises the following steps: cysteamine hydrochloride (3.05g), potassium hydroxide (1.5g), sodium bicarbonate (6.75g), 50mL of water was added. After the addition, acetic anhydride (2.28mL) was slowly added dropwise over 5min, and the reaction was carried out for 0.5 to 1 h. Detecting by Thin Layer Chromatography (TLC), adjusting the pH to be neutral by 1mol/L hydrochloric acid, extracting by twice volume of ethyl acetate, and separating by silica gel column to obtain the SNAC.

2) Separation of

Centrifuging the fermentation liquor (50L) at 4000r/min for 30min, taking the supernatant, extracting twice (100L) with equal volume of ethyl acetate, drying the ethyl acetate phase, performing rotary evaporation concentration, and concentrating to obtain 10.5g of crude extract. Removing part of impurities in the concentrated extractive solution by silica gel column chromatography, wherein the eluent of silica gel column chromatography (3cm × 110cm) sequentially comprises: petroleum ether (2.5L), petroleum ether ethyl acetate (1:1, v/v) (2.5L), ethyl acetate (5L), ethyl acetate methanol (1:1, v/v) (5L), methanol (2.5L), palsmimycin A was concentrated mainly in ethyl acetate methanol (1:1, v/v) phase, which was concentrated and weighed 5.2 g. After concentration and drying, the column was chromatographed on a C18 reverse phase packed column (3 cm. times.90 cm) eluting with water (1L), 10% acetonitrile (1.5L), 30% acetonitrile (1.5L), 50% acetonitrile (2L), acetonitrile (1.5L), methanol (2L) in this order, palsmimycin A being concentrated mainly in the 50% acetonitrile phase. The above 50% acetonitrile phase was subjected to rotary evaporation to remove the organic phase, and freeze vacuum drying to remove water, to obtain 2.5g of a crude isolated product.

3) Purification of

Dissolving the crude separation product in 15mL of acetonitrile, filtering by a 0.22-micron membrane, carrying out primary purification by an active Zorbax SB-C18(9.4 multiplied by 250mm, 5-micron membrane, active, Santa Clara, CA, USA) and a Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan), adopting acetonitrile and water (0.06% formic acid) as a mobile phase, the flow rate is 2mL/min, preparing by using 40% acetonitrile with equal concentration, the sample injection volume is 50 muL, sequentially collecting an elution component with the retention time of 12.5-13.0 min as a component 1, collecting an elution component with the retention time of 13.4-14.0 min as a component 2, collecting an elution component with the retention time of 17.2-17.9 min as a component 3, collecting an elution component with the retention time of 18.2-19.3 min as a component 4, collecting an elution component with the retention time of 21.0-21.8 min as a component, collecting an elution component with the retention time of 19.2-19.3 min as a component 4, collecting an elution component with the retention time of 20.8-20.8 min as a component, collecting the elution component with the retention time of 24.0-26.0 min as component 8. The components and their masses (mg) were obtained as follows:

wherein, the palsmimycin A is mainly concentrated in the component 3 and the component 4.

Performing secondary refining by using Aglient Zorbax SB-C18(9.4 multiplied by 250mm,5 mu m, Aglient, Santa Clara, CA, USA) and Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan), using water (0.06% formic acid) and acetonitrile as A, B mobile phases respectively, purifying by using acetonitrile isoconcentration gradient with volume fraction of 43% at the flow rate of 2mL/min and sample injection volume of 60 mu L, and collecting eluent with retention time of 12.0-13.0 min; purified palsmimycin A, 11.7mg, was obtained by rotary evaporation, concentration, freeze vacuum drying.

Structure confirmation data for palsmimycin A:

HRMS/ESI gives the chemical composition C₄₂H₆₄N₄O₁₉S₃(m/z:[M+Na]⁺Is 1047.3259, [ M + Na]⁺Calculated value 1047.3327, relative error 3.9ppm), characteristic absorption peak λ in the UV spectrum_maxAt 246nm, 277nm, and 321nm, respectively, two molecules of SNAC were presumably added to the paulonic acid moiety of paulomycin A.

By reaction with paulomycin A¹The H-NMR spectra are compared, and the signals of the palsmimycin A and the paulomycin A are very similar, except that the signals of the carbon-carbon double bond of the paulomycin A are lacked, and the signals of two molecules of SNAC are increased. The appearance of the H-2 '(5.08) signal and the reduction in the shift of the H-3' signal in palsimycin A compared to paulomycin A (6.83 to 3.53) indicates that one molecule of SNAC undergoes Michael addition to the double bond of paulonic acid in paulomycin A and that the correlation of H-3 'to the HMBC of C-1' further corroborates the above inference. While the association of the HMBC at C-5 "by H-1", confirms that another molecule of SNAC is attached to the isothiocyanate group of paul acid by nucleophilic addition. Detailed 2D NMR correlation analyses (including HSQC, HMBC, gamma-gamma,¹H-¹H COSY spectrum) confirmed the structure of palsmimycin a (as shown in fig. 3).

Palsimycin A:¹H NMR(500MHz,acetone-d₆):5.36(q,J＝6.8Hz,1H,H-7'),5.13(m,1H,H-1'),5.08(d,J＝6.6Hz 1H,H-2"),4.77(dd,J＝2Hz,10Hz,1H,H-11),4.49(q,J＝6.8Hz,1H,H-5'),4.23(m,1H,H-10),4.10(m,1H,H-12),3.94,3.88(m,2H,H-13),3.82(d,J＝10Hz,1H,H-8),3.68(m,1H,H-9),3.64(m,1H,H-3'),3.53(m,1H,H-3"),3.40(m,2H,H-2"""),3.35(s,3H,H-3'-OMe),3.31(t,J＝7Hz,2H,H-1"""),3.26,3.50(m,2H,H-2""'),3.16(m,2H,H-5),2.64,2.77(m,2H,H-1""'),2.45(m,1H,H-2"'),2.00(s,3H,H-2""),1.96,2.24(m,2H,H-2'),1.94(s,3H,H-4"""),1.88(s,3H,H-4""),1.72,1.53(m,2H,H-3"'),1.35(d,J＝6.8Hz,3H,H-4"),1.29(d,J＝6.8Hz,3H,H-8'),1.24(d,J＝6.8Hz,3H,H-6'),1.18(d,J＝7.0Hz,3H,H-4"'),0.96(t,J＝7.0Hz,3H,H-5"').¹³C NMR(125MHz,acetone-d₆):199.6,199.2,188.8,175.6,175.6,171.1,170.6,170.2,168.4,159.8,99.5,99.5,78.6,76.9,76.9,74.9,74.1,72.6,70.4,69.8,68.2,68.2,64.6,63.2,57.1,48.4,41.9,40.4,39.2,38.5,34.6,31.4,31.1,27.1,22.8,22.6,20.5,18.9,17.2,15.8,15.7,11.8.

4) Evaluation of biological Activity

Selecting gram-positive bacteria: staphylococcus aureus (Staphylococcus aureus CGMCC 1.89), Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis (Staphylococcus epidermidis ATCC 35984), Enterococcus faecalis (Enterococcus faecalis1.14), Streptococcus pyogenes (Streptococcus pyogenes), Streptococcus pneumoniae (Streptococcus pneumoniae) as test strains, a primary screen for antibacterial activity by a paper sheet method, and a secondary screen for antibacterial activity by a paper sheet method, a secondary dilution method, 5 μ L of the test strains are dripped on a 6mm sterile filter paper sheet, and the antibacterial sizes of the circles of the paper sheet A, the paper sheet A and the paper sheet B are compared by taking DMSO as a negative control.

The test strains were cultured in Mueller-Hinton (MH) broth for 12h at 37 ℃ and 220rpm, and diluted to 1X 10⁵CFU/mL. palsimycin A, paulomycin A and paulomycin B are dissolved in DMSO with a certain concentration, 5 mu L of the dissolved palsimycin A, paulomycin A and paulomycin B are added into 195 mu L of sterile MH broth, a 96-well plate method is adopted for serial dilution, 100 mu L of the diluted final dilution is discarded, 100 mu L of the diluted bacterial suspension is added into a small well, and positive and negative controls are set. The final concentration of DMSO is not more than 5%. Incubate at 37 ℃ for 24h and read the MIC values. Each set of experiments was repeated three times. The results are shown in Table 1.

5) Evaluation of stability

The percentage retention of palsimycin a after 12h, 36h standing at 25 ℃ under acidic (pH 2) and basic conditions (pH 9) was evaluated mainly and compared to paulomycin a, paulomycin B in triplicate for each set of experiments. The results are shown in Table 2.

Example 2 isolation and purification of Palsimycin B and evaluation of biological Activity and stability

1) Fermentation of

The same as in example 1.

2) Separation of

The same as in example 1. palsmimycin B was mainly concentrated in the 50% acetonitrile phase. The above 50% acetonitrile phase was subjected to rotary evaporation to remove the organic phase, and freeze vacuum drying to remove water, to obtain 2.5g of a crude isolated product.

3) Purification of

Dissolving the crude separation product in 15mL of acetonitrile, filtering by a 0.22-micron membrane, carrying out primary purification by an active Zorbax SB-C18(9.4 multiplied by 250mm, 5-micron membrane, active, Santa Clara, CA, USA) and a Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan), adopting acetonitrile and water (0.06% formic acid) as a mobile phase, the flow rate is 2mL/min, preparing by using 40% acetonitrile with equal concentration gradient, the sample injection volume is 50 muL, sequentially collecting an elution component with the retention time of 12.5-13.0 min as a component 1, collecting an elution component with the retention time of 13.4-14.0 min as a component 2, collecting an elution component with the retention time of 17.2-17.9 min as a component 3, collecting an elution component with the retention time of 18.2-19.3 min as a component 4, collecting an elution component with the retention time of 21.0-21.8 min as a component, collecting an elution component with the retention time of 19.5-19.3 min as a component, collecting an elution component with the retention time of 20.8-20.8 min as a component, collecting the elution component with the retention time of 240-260 min and marking as a component 8. The components and their masses (mg) were obtained as follows:

wherein, the palsmimycin B is mainly concentrated in the component 1 and the component 2.

Secondary refining was performed using an active Zorbax SB-C18 (9.4X 250mm,5 μm, active, Santa Clara, CA, USA), Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan) with water (0.06% formic acid), acetonitrile as A, B mobile phase, flow rate of 2mL/min,60 μ L injection volume, gradient elution according to acetonitrile percentage in the following time program: 35% in 0-3 min; 35-40% of 3-8 min; 8-13 min, 40% -43%; 13-20 min, 43% -50%; 20-22 min, 50% -100%; 22-24 min, 100%; 24-26 min, 100% -50%; 26-30 min, 50-35%. Collecting the eluent with the retention time of 18.0-19.0 min; purified palsmimycin B12 mg was obtained by rotary evaporation, concentration, freeze vacuum drying.

Structure corroboration data for Palsimycin B:

HRMS/ESI gives the chemical composition C₄₁H₆₂N₄O₁₉S₃(m/z:[M+Na]⁺Is 1033.3068, [ M + Na]⁺Calculated value 1033.3170, relative error 0.54ppm), characteristic absorption peak λ in the UV spectrum_maxAt 246nm, 277nm, and 322nm, respectively, the difference from paulomycin B is the absorption of the paulonic acid moiety, and it is assumed that two molecules of SNAC are added to the paulonic acid moiety of paulomycin B.

By reaction with paulomycin B¹The H-NMR spectra are compared, and the signals of the palsmimycin B and the paulomycin B are very similar, except that the signals of the carbon-carbon double bond of the paulomycin B are lacked, and the signals of two molecules of SNAC are increased. The appearance of the H-2 '(5.08) signal and the reduction in the shift of the H-3' signal in palsimycin B compared to paulomycin B (6.82 to 3.52) indicates that one molecule of SNAC undergoes Michael addition to the double bond of paulonic acid in paulomycin B and that the correlation of H-3 'to the HMBC of C-1' further corroborates the above inference. While the association of the HMBC at C-5 "by H-1", confirms that another molecule of SNAC is attached to the isothiocyanate group of paul acid by nucleophilic addition. Detailed 2D NMR correlation analyses (including HSQC, HMBC, gamma-gamma,¹H-¹H COSY spectrum) confirmed the structure of palsmimycin B as shown in fig. 8.

Palsimycin B:¹H NMR(500MHz,acetone-d₆):5.35(q,J＝6.0Hz,1H,H-7'),5.13(d,J＝2Hz,1H,H-1'),5.08(m,1H,H-2"),4.78(dd,J＝2Hz,8Hz,1H,H-11),4.51(q,J＝6.0Hz,1H,H-5'),4.23(m,1H,H-10),4.13(m,1H,H-12),3.95-3.86(m,2H,H-13),3.83(d,J＝10Hz,1H,H-8),3.70(m,1H,H-9),3.65(dd,J＝4.85Hz,11.0Hz,1H,H-3'),3.52(m,1H,H-3"),3.41(m,2H,H-2""”),3.34(s,3H,H-3'-OMe),3.32(m,2H,H-1""”),3.29(m,2H,H-2""'),3.16(m,2H,H-5),2.78(m,2H,H-1”'"),2.65(m,1H,H-2"'),2.00(s,3H,H-2""),1.98,2.24(m,2H,H-2'),1.94(s,3H,H-4"""),1.88(s,3H,H-4""'),1.35(d,J＝6.85Hz,3H,H-4"),1.28(d,J＝6.85Hz,3H,H-8'),1.24(d,J＝6.0Hz,3H,H-6'),1.20(d,J＝7.0Hz,3H,H-4"'),1.18(d,J＝7.0Hz,3H,H-3"').¹³C NMR(125MHz,acetone-d₆):199,198,188.1,175.5,175.5,169.9,169.7,169.2,167.8,159.2,99.8,98.8,78,77.9,76.1,74.2,73.5,71.9,70,69.8,69.2,67.4,63.9,62.4,56.4,47.7,39.7,39.7,38.7,33.9,30.4,30.4,22.1,21.9,19.8,18.7,18.6,15.2,15.

4) Evaluation of biological Activity

The same as in example 1. The results are shown in Table 1.

5) Evaluation of stability

The percentage retention of palsimycin B after 12h, 36h at 25 ℃ under acidic (pH 2) and basic conditions (pH 9) was evaluated mainly and compared to paulomycin a, paulomycin B in triplicate for each set of experiments. The results are shown in Table 2.

Example 3 isolation and purification of palsmimycin C and evaluation of biological Activity and stability

1) Fermentation of

The same as in example 1.

2) Separation of

The same as in example 1. palsmimycin C was mainly concentrated in the 50% acetonitrile phase. The above 50% acetonitrile phase was subjected to rotary evaporation to remove the organic phase, and freeze vacuum drying to remove water, to obtain 2.5g of a crude isolated product.

3) Purification of

Dissolving the crude separation product in 15mL of acetonitrile, filtering by a 0.22-micron membrane, carrying out primary purification by an active Zorbax SB-C18(9.4 multiplied by 250mm, 5-micron membrane, active, Santa Clara, CA, USA) and a Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan), adopting acetonitrile and water (0.06% formic acid) as a mobile phase, the flow rate is 2mL/min, preparing by using 40% acetonitrile with equal concentration gradient, the sample injection volume is 50 muL, sequentially collecting an elution component with the retention time of 12.5-13.0 min as a component 1, collecting an elution component with the retention time of 13.4-14.0 min as a component 2, collecting an elution component with the retention time of 17.2-17.9 min as a component 3, collecting an elution component with the retention time of 18.2-19.3 min as a component 4, collecting an elution component with the retention time of 21.0-21.8 min as a component, collecting an elution component with the retention time of 19.5-19.3 min as a component, collecting an elution component with the retention time of 20.8-20.8 min as a component, collecting the elution component with the retention time of 24.0-26.0 min as component 8. The components and their masses (mg) were obtained as follows:

wherein, the palsmimycin C is mainly concentrated in the component 6 and the component 7.

The palsmimycin C is purified by using Aglient Zorbax SB-C18(9.4 multiplied by 250mm,5 mu m, Aglient, Santa Clara, CA, USA) and Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan) for secondary refining, using water (0.06 percent formic acid) and acetonitrile as A, B mobile phases respectively, the flow rate is 2mL/min, the sample injection volume of 60 mu L, acetonitrile with the volume fraction of 46 percent and other concentration gradients, collecting the eluent when 11.5-13.0 min, and obtaining the purified palsmimycin C4.2 mg after rotary evaporation concentration, freezing and vacuum drying.

Structural corroboration data for palsimycin C:

HRMS/ESI gives the chemical composition C₃₇H₅₃N₃O₁₈S₂(m/z:[M+Na]⁺Is 892.2840, [ M + Na]⁺Calculated value 892.2766, relative error 0.19ppm), characteristic absorption peak λ in the UV spectrum_maxAt 239nm and 321nm, respectively, the palsimicin C is distinguished from paulomycin B by the absorption of the paulonic acid moiety, and it is presumed that a molecule of SNAC is added to the paulonic acid moiety of paulomycin B based on the molecular weight.

By reaction with paulomycin B¹The H NMR spectra were compared and found to be very similar to the signals of palsimicin C and paulomycin B, except that the signal of the carbon-carbon double bond of paulomycin B was absent and a molecule of SNAC was added. Comparison of the H-2' (5.10) signal in palsmimycin B with that of paulomycin BThe appearance and decrease in the shift of the H-3' signal (6.82 to 3.51) indicates that one molecule of SNAC undergoes Michael addition with the double bond of paulonic acid in paulomycin B, as shown in FIG. 17.

Palsimycin C:¹H NMR(500MHz,acetone-d₆):5.36(q,J＝6.8Hz,1H,H-7'),5.10(d,J＝5Hz 1H,H-2"),5.04(m,1H,H-1'),4.77(dd,J＝2Hz,9Hz,1H,H-11),4.56(q,J＝6.3Hz,1H,H-5'),4.24(m,1H,H-10),4.15(m,1H,H-12),3.94,3.85(m,2H,H-13),3.84(d,J＝10Hz,1H,H-8),3.70(m,1H,H-9),3.65(m,1H,H-3'),3.51(m,1H,H-3"),3.50(m,2H,H-2""'),3.34(s,3H,H-3'-OMe),3.31,3.23(m,2H,H-1""'),3.17(m,2H,H-5),2.64(m,1H,H-2"'),2.00(s,3H,H-2""),1.94,2.22(m,2H,H-2'),1.88(s,3H,H-4""'),1.35(d,J＝6.8Hz,3H,H-4"),1.29(d,J＝6.8Hz,3H,H-8'),1.24(d,J＝6.3Hz,3H,H-6'),1.21(d,J＝7.0Hz,3H,H-3"'),1.18(d,J＝7.0Hz,3H,H-4"').

4) Evaluation of biological Activity

The same as in example 1. The results are shown in Table 1.

5) Evaluation of stability

The percentage retention of palsimycin C after 12h, 36h at 25 ℃ under acidic (pH 2) and basic conditions (pH 9) was evaluated mainly and compared to paulomycin a, paulomycin B in triplicate for each set of experiments. The results are shown in Table 2.

Example 4 isolation and purification of Palsimycin D and evaluation of biological Activity and stability

1) Fermentation of

The same as in example 1.

2) Separation of

The same as in example 1. palsmimycin D was mainly concentrated in the 50% acetonitrile phase. The above 50% acetonitrile phase was subjected to rotary evaporation to remove the organic phase, and freeze vacuum drying to remove water, to obtain 2.5g of a crude isolated product.

3) Purification of

of these, palsmimycin D was mainly concentrated in fraction 5. The palsmimycin D was purified by secondary purification using Aglient Zorbax SB-C18 (9.4X 250mm,5 μm, Aglient, Santa Clara, CA, USA) and Shimadzu high performance liquid phase (Shimadzu, Kyoto, Japan) using water (0.06% formic acid) and acetonitrile as A, B mobile phases, at a flow rate of 2mL/min, at a sample injection volume of 60 μ L, with a concentration gradient of 45% acetonitrile, etc., and subjected to rotary evaporation concentration and freeze vacuum drying to obtain 4.1mg of purified palsmimycin D.

Structure corroboration data for Palsimycin D:

HRMS/ESI gives the chemical composition C₃₇H₅₃N₃O₁₈S₂(m/z:[M+Na]⁺Is 892.2840, [ M + Na]⁺Calculated value 892.2766, relative error 0.19ppm), characteristic absorption peak λ in the UV spectrum_maxAt 237nm and 321nm, the palsimycin D was distinguished from paulomycin B by the absorption of the paulonic acid moiety, while it was presumed that a molecule of SNAC was added to the paulonic acid moiety of paulomycin B based on the molecular weight.

By interaction with palsmimycin C¹Comparing H NMR spectra, finding that the signals of palsmimycin D and palsmiycin C are very similar, analyzing HMBC spectrum of palsmiycin D, finding that signals related to H-3 'and C-5' are provided, confirming that SNAC of one molecule firstly carries out nucleophilic addition with isothiocyanate, and then carries out M with carbon-carbon double bondThe addition of ichael forms the structure of a five-membered heterocyclic ring in the acid moiety. Detailed 2D NMR correlation analyses (including HSQC, HMBC, gamma-gamma,¹H-¹H COSY spectrum) confirmed the structure of palsmimycin D as shown in fig. 20.

Palsimycin D:¹H NMR(500MHz,acetone-d₆):5.35(q,J＝6.0Hz,1H,H-7'),5.13(d,J＝2.0Hz,1H,H-1'),5.08(m,1H,H-2"),4.78(dd,J＝2Hz,8Hz,1H,H-11),4.51(q,J＝6.0Hz,1H,H-5'),4.23(m,1H,H-10),4.13(m,1H,H-12),3.95-3.86(m,2H,H-13),3.83(d,J＝10Hz,1H,H-8),3.70(m,1H,H-9),3.65(dd,J＝4.85Hz,11.0Hz,1H,H-3'),3.52(m,1H,H-3"),3.34(s,3H,H-3'-OMe),3.29(m,2H,H-2""'),3.18(m,2H,H-5),2.78(m,2H,H-1""'),2.65(m,1H,H-2”'),2.00(s,3H,H-2""),1.98,2.24(m,2H,H-2'),1.88(s,3H,H-4"'"),1.35(d,J＝6.85Hz,3H,H-4"),1.28(d,J＝6.85Hz,3H,H-8'),1.24(d,J＝6.0Hz,3H,H-6'),1.20(d,J＝7.0Hz,3H,H-4"'),1.18(d,J＝7.0Hz,3H,H-3"').

¹³C NMR(125MHz,acetone-d₆):197.5,187.4,175.1,169.3,168,167,158.5,97.7,79.1,77.3,77.1,74.6,73.5,72.8,71.2,69.1,69,68.5,66.6,61.4,55.6,48.5,47.1,38.4,33.2,31,29.6,21.2,19.1,18,17.1,15.9,14.5,14.3.

4) The bioactivity was evaluated as in example 1. The results are shown in Table 1.

5) Evaluation of stability

The percentage retention of palsimycin D after 12h, 36h at 25 ℃ under acidic (pH 2) and basic conditions (pH 9) was evaluated primarily and compared to paulomycin a, paulomycin B in triplicate for each set of experiments. The results are shown in Table 2.

TABLE 1 comparison of antibacterial Activity of palsimycins A-D with Paulomycins A, B (. mu.g/mL)

The antibacterial activity of palsimycin A, B, C, D was evaluated by broth microdilution using gram-positive strains Staphylococcus aureus (Staphylococcus aureus CGMCC 1.89), Methicillin-resistant Staphylococcus (Methicillin-resistant Staphylococcus aureus, MRSA), Staphylococcus epidermidis (Staphylococcus epidermidis ATCC 35984), Enterococcus faecalis (Enterococcus faecium 1.14), Streptococcus pyogenes (Streptococcus pyogenes), Streptococcus pneumoniae (Streptococcus pneumoniae) as test strains, and compared with paulomycin A, paulomycin B and with vancomycin as a positive control. The results of the experiments are shown in table 1, the antibacterial activity of palsimycin a and palsimycin B on each test strain is at the same level as that of paulomycin a and paulomycin B, while the antibacterial activity of paulomycin derivatives palsimycin C and paulomycin D modified by a molecule SNAC is weaker than that of paulomycin a and paulomycin B. In addition, the antibacterial activity of the palsmycin D containing a special five-ring structure is obviously better than that of the palsmicin C which adds one molecule of SNAC at the position of the carbon-carbon double bond of the paulonic acid. The Minimum Inhibitory Concentrations (MICs) of palsimycin A, palsimycin B and paulomycin A, paulomycin B for each test strain except Streptococcus pneumoniae were of the same order of magnitude as the positive control vancomycin.

TABLE 2 stability evaluation of palsimycins A-D

Similar to paulomycin in nature, palsimycin A-D is heat sensitive and unstable under acidic and basic conditions. Under acidic condition, the A ring hydroxyl is dehydrated, and the solution is changed from colorless to light yellow to lose biological activity. As can be seen from Table 2, at pH 2, palsimycin A-D degraded more slowly than paulomycin A and paulomycin B, with paulomycin A-D remaining 51%, 60%, 42% and 32% after 36h, respectively, while paulomycin A and paulomycin B degraded 88% and 77% respectively. Under the alkaline condition (pH is 9), the palsimycin A-D respectively retains 76%, 83%, 89% and 84% after being placed at 25 ℃ for 12h, and the paulomycin A and the paulomycin B respectively retain 49% and 50%; after being placed for 36h, the palsimycin A-D (48%, 50%, 54%, 58%) degraded more slowly than the paulomycin A and paulomycin B retained (33%, 31%). Thus, palsimycin A-D is more stable under both acidic and basic conditions than either paulomycin A or paulomycin B.

Claims

1. A compound having a structural formula as shown in formula I:

the compound shown in the formula I is specifically palsmimycin A, palsmimycin B, palsmimycin C or palsmimycin D, and the structural formula is shown as follows:

2. a process for the preparation of a compound according to claim 1, comprising the steps of:

1) performing fermentation culture on Streptomyces paulus NRRL8115 strain in a liquid culture medium containing N-acetylcysteamine, and collecting fermentation liquid;

separating the concentrate by C18 reversed phase packed column chromatography, wherein the elution phases are sequentially: water, acetonitrile-water solution with volume fraction of 10% in 1 time of column volume, acetonitrile-water solution with volume fraction of 30% in 1.5-2 time of column volume, and acetonitrile-water solution with volume fraction of 50% in 1-1.5 time of column volume, collecting elution components eluted by the acetonitrile-water solution with volume fraction of 50%, removing an organic phase, and drying to obtain a crude separation product;

3) preparing the crude separation product into a solution by taking acetonitrile as a solvent; then separating by using a reversed-phase high performance liquid chromatography, taking acetonitrile and water containing 0.06% of acetic acid as mobile phases, performing equal concentration gradient elution on the acetonitrile and the water containing 0.06% of acetic acid according to a volume ratio of 4:6, sequentially collecting elution components with retention time of 12.5-13.0 min as a component 1, collecting elution components with retention time of 13.4-14.0 min as a component 2, collecting elution components with retention time of 17.2-17.9 min as a component 3, collecting elution components with retention time of 18.2-19.3 min as a component 4, collecting elution components with retention time of 21.0-21.8 min as a component 5, collecting elution components with retention time of 19.4-19.8 min as a component 6, collecting elution components with retention time of 20.2-20.8 min as a component 7, and collecting elution components with retention time of 24.0-26.0 min as a component 8;

3. The method of claim 2, wherein: in the step 1), the volume fraction of the N-acetylcysteamine in the liquid culture medium containing the N-acetylcysteamine is 0.1 to 0.2 percent;

the conditions of the fermentation culture are as follows: culturing at 28 ℃ for 36-48 h;

the inoculation amount of the Streptomyces paulus NRRL8115 is 2-4%.

4. The production method according to claim 2 or 3, characterized in that: in the step 3), the chromatographic conditions of the reversed-phase high performance liquid chromatography are as follows: the chromatographic column is an agent Zorbax SB-C18 with the specification of 9.4 multiplied by 250mm and 5 μm; the flow rate was 2 mL/min.

5. Use of a compound of claim 1 or a pharmaceutically acceptable salt or ester thereof for the manufacture of a medicament against gram-positive bacteria.

6. Use according to claim 5, characterized in that: the gram-positive bacterium is at least one of: staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Streptococcus pyogenes, and Streptococcus pneumoniae.

7. A pharmaceutical against gram-positive bacteria, comprising as an active ingredient a palsmimycin A, a palsmimycin B or a palsmimycin D as claimed in claim 1 or a pharmaceutically acceptable salt, ester thereof.